BoilerFaultCodes 30 70 High
Boiler Fault Code 30 70
Also written as 3070 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 30 70 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to switch between heating your radiators and providing hot water, meaning you likely have no hot water from your taps. (As reported on Chaffoteaux Serelia 24 MFFI)
Pick your boiler brand for the 30 70 fix
Source
Information for the 30 70 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026